Malnutrition affects over one third of patients with cystic fibrosis (CF), and has been directly linked to increased morbidity and mortality. Human recombinant growth hormone (GH) has proven effective for treatment of malnutrition in AIDS and other chronic illnesses. The hypothesis of this study is the anabolic effects of GH will reverse protein malnutrition and improve the nutritional and clinical status of malnourished CF patients. This randomized study will treat 10 malnourished CF patients with GH compared to 10 CF control patients. To date, 13 children have been enrolled, 7 treated with growth hormone, and 6 untreated. Each has completed 3 months of the study. Ten have completed 12 months of the study, and three have completed three months. After one year of the study, the children treated with growth hormone demonstrated significant increase in height, height velocity, weight, weight velocity, and lean body mass compared to the nontreated children. The treated children also demonstrated significant reduction in the number of hospitalizations compared to their pre-treatment year.